I have squirrel hunted with handguns since 1960, using multiple examples of Ruger Single Sixes, FA 252 and 97, Ruger Mk. I and II's, S&W 17, and T/C Contenders.
If one is limited to a revolver or single shot, as in Pa., the FA 97 is the best of the lot in my opinion, but personally, I have been satisfied with most of my Single Sixes, too. The one shown in the second photo below is equally accurate with the LR or WMR cylinder, if one shoots the unobtainium Winchester .22 Mag JHP ammo.




In my opinion, the very best bang for the buck is the Ruger Mk. II or III series. I have seen nothing else giving equal value. I prefer the Mk. II.



I have used and on occasion continue to use iron sights for small game hunting, but all my serious squirrel guns wear Leupold scopes